Redox amplification for ultrasensitive amperometric detection in flowing streams

摘要

A signal enhancement method for amperometric electrochemical detection of redox-active analytes in flowing strams is described. The method is based on a continuous regeneration of electrooxidized analytes in an electrochemical flow cell by reaction with a sacrificial electron donor in solution. Ultrasensitive detection of ferrocenes using ferrocyanide as electron donor is demonstrated. Signal amplification factors of up to 170x were obtained for ferrocene injections in a concentraton range between 10~(-4) and 10~(-7) M where peaks could be discerned both with and without amplification. Discernable peaks were obtained with amplification for ferrocene injections at much lower concentrations, in the picomolar concentration range and below.